Move member function rootEditableElement() out from VisiblePosition class

Source/core/editing/VisiblePosition.h

 /*
  * Copyright (C) 2004, 2008 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 75 matching lines @@
 
     bool isNull() const { return m_deepPosition.isNull(); }
     bool isNotNull() const { return m_deepPosition.isNotNull(); }
     bool isOrphan() const { return m_deepPosition.isOrphan(); }
 
     Position deepEquivalent() const { return m_deepPosition; }
     Position toParentAnchoredPosition() const { return deepEquivalent().parentAnchoredEquivalent(); }
     PositionWithAffinity toPositionWithAffinity() const { return PositionWithAffinity(m_deepPosition, m_affinity); }
     TextAffinity affinity() const { return m_affinity; }
 
-    // TODO(yosin) This does not handle [table, 0] correctly.
-    Element* rootEditableElement() const { return m_deepPosition.isNotNull() ? m_deepPosition.anchorNode()->rootEditableElement() : 0; }
-
     DECLARE_TRACE();
 
 #ifndef NDEBUG
     void debugPosition(const char* msg = "") const;
     void formatForDebugger(char* buffer, unsigned length) const;
     void showTreeForThis() const;
 #endif
 
 private:
     template<typename Strategy>
@@ skipping 41 matching lines @@
 
 } // namespace blink
 
 #ifndef NDEBUG
 // Outside the WebCore namespace for ease of invocation from gdb.
 void showTree(const blink::VisiblePosition*);
 void showTree(const blink::VisiblePosition&);
 #endif
 
 #endif // VisiblePosition_h